backfire ??
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Elder User
Joined: Sep 2002
Posts: 622
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From: Urbandale, Iowa
backfire ??
My 68 390 has developed a little pop this evening. Whilst reving the engine to heat it up after a thermostat replacement, I got a backfire as it would idle down. I have replaced the sparkplugs, but I had not noticed the backfire before. This is not to say that it wasn't there, mind you. I haven't driven the truck since bringing it home, and only started it after replacing the battery cables, oil & filter, air filter, spark plugs, and now, thermostat and heater hoses.
I have not messed with the distributor (yet).
Any ideas?
Thanks!
I have not messed with the distributor (yet).
Any ideas?
Thanks!
Posting Guru
Joined: Aug 2002
Posts: 1,214
Likes: 2
From: Minneapolis, MN
backfire ??
Pat, does it pop back through the carb or is the exhaust popping? Is it more or less constant or just when decelerating? Some things to start with: If it's in the exhaust it could be as simple as a slight air leak in the exhaust. If it's coming from the carb check your plug wires (crossed or crossfiring). Also check the timing.
Just my $.02 I'm sure others will pitch in also.
Greg
'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
huct on foniks wurkt fer me
Just my $.02 I'm sure others will pitch in also.
Greg
'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
huct on foniks wurkt fer me
Thread Starter
|
Elder User
Joined: Sep 2002
Posts: 622
Likes: 0
From: Urbandale, Iowa
backfire ??
>Pat, does it pop back through the carb or is the exhaust
>popping? Is it more or less constant or just when
>decelerating? Some things to start with: If it's in the
>exhaust it could be as simple as a slight air leak in the
>exhaust. If it's coming from the carb check your plug wires
>(crossed or crossfiring). Also check the timing.
>Just my $.02 I'm sure others will pitch in also.
>Greg
>
>'77 F-250 Camper Special 400ci driver
>'76 F-250 Supercab 360ci current project
>'71 Mach I 429CJ in storage
>'79 F-150 for parts
>huct on foniks wurkt fer me
Hi Greg, thanks.
It only happens upon deceleration, and seems to be through the exhaust only (which has HUGE leaks at the manifolds and almost certainly further back as the only thing holding the whole system up is that it's rusted to the hangers
)
Pat
>popping? Is it more or less constant or just when
>decelerating? Some things to start with: If it's in the
>exhaust it could be as simple as a slight air leak in the
>exhaust. If it's coming from the carb check your plug wires
>(crossed or crossfiring). Also check the timing.
>Just my $.02 I'm sure others will pitch in also.
>Greg
>
>'77 F-250 Camper Special 400ci driver
>'76 F-250 Supercab 360ci current project
>'71 Mach I 429CJ in storage
>'79 F-150 for parts
>huct on foniks wurkt fer me
Hi Greg, thanks.
It only happens upon deceleration, and seems to be through the exhaust only (which has HUGE leaks at the manifolds and almost certainly further back as the only thing holding the whole system up is that it's rusted to the hangers
)Pat
Posting Guru
Joined: Aug 2002
Posts: 1,214
Likes: 2
From: Minneapolis, MN
backfire ??
Hey Pat, Sounds like it's just exhaust leaks. When you let off the gas the unburned fuel mixture gets into the exhaust. If the system leaks it lets air in through the leaks which allows that unburnt fuel to ignite.
It shouldn't hurt anything but it sure gets annoying. 
Greg
'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
huct on foniks wurkt fer me
It shouldn't hurt anything but it sure gets annoying. Greg
'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
huct on foniks wurkt fer me
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